Thermoforming machines are generally used for forming flat sheets made from a material, which can be formed when heated, through form sections with cavities disposed therein, wherein the internal shape of each cavity corresponds to the outer shape of an object to be formed in the cavity. Thermoforming machines are well known and comprise e.g. material loading devices, heating devices, forming devices, unloading devices, etc. The technology to process thermoplastic or thermocurable materials with relatively large sizes through thermoforming machines has developed in response to increasing demands in various industries.
The applicant is e.g. familiar with a thermoforming machine, which is provided as a “twin sheet thermo former”, this means as a thermoforming machine, in which two parts can be manufactured simultaneously. This thermoforming machine has an upper and a lower plate, which can be adjusted with respect to their elevation relative to a frame through motors. Hydraulic pistons are attached to the upper plate, which can be connected in a solid manner through a form-fit connection via connecting elements to the lower plate. Thus the piston rods are inserted into associated opposite elements, and secured to them in a form-fitting manner. Through the operation of the hydraulic pistons, thus the lower and the upper plate can be strongly pulled against each other.
In this approach it has proven to be disadvantageous, that, due to this form-fitting arrangement, damages in the connecting elements can occur when a certain pulling force is exceeded, so that these have to be replaced or repaired. During this time period the thermoforming machine is out of service and productivity declines in an undesirable manner.